Boston and Miami, Part IV, presents that rarity of rarities in an NBA regular-season game -- actual meaning. The teams, which meet Sunday in Miami, are tied for second place in the Eastern Conference with records of 55-24. The winner likely will secure the No. 2 seed behind the Chicago Bulls for the playoffs, which begin next weekend.

Each team will still have two games to play after this South Beach Armageddon. Boston will travel to Washington for a Monday night game -- yes, the dreaded back-to-back on the road -- and Miami visits Atlanta the same night. On Wednesday, the Celtics close at home against the New York Knicks and the Heat will take their collective talents north of the border to finish at Toronto.

"This is a big game for us,'' said the Celtics' Paul Pierce. "That's what we are playing for, for the home-court advantage. Not only for the first round, but hopefully we will see them in the second round. This is a big game for us when you are talking about seeds and trying to advance in the playoffs. It's huge."

With that in mind, here are some things to look for Sunday when the teams most thought at the beginning of the season would battle for No. 1 are, instead, battling for No. 2.

Seeding: Miami must finish the season with a better record than the Celtics to get the higher seed. If the teams finish with identical records, the Celtics get the higher seed by virtue of having already clinched the season series. So, to slip into hockey parlance for a moment, this is your basic four-pointer. A Boston win would give the Celtics a one-game lead with two games to play. But in reality, it would be a two-game lead because of the advantage in the head-to-head category. A Miami win would give the Heat that one-game lead, but they'd likely have to win out to keep it.

But here's an interesting twist, as well. The Heat, Celtics and Lakers all have 55-24 records. If you assume that L.A. is going to get out of the West, then what would happen if (a) either Boston or Miami got out of the East and (b) the Eastern winner and the Lakers finished with the same record?

Well, if it's Miami, the Heat get home court in the Finals because of their 2-0 record over the Lakers in head-to-head play. If it's the Celtics, the Lakers get home court because of their superior record in out-of-conference play (21-9 vs. the Celtics' 19-11). See, all those losses at home to Western Conference teams could come back to bite the Celtics you know where.

Shaq: The last time these teams met in Miami, on Nov. 11, Shaquille O'Neal returned from a five-game injury absence to help the Celtics beat the Heat 112-107. In that game, Ray Allen scored 35 points, the most by a Celtic this season and one of seven times that a Celtic has gone for 30 or more points. (By comparison, the Heat have had a player go for 30 or more points 53 times this season, with LeBron James and Wade accounting for 49 of those games.)

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Alas, Shaq will not be making another return from injury for the Celtics' second visit to South Beach. Team spokesman Jeff Twiss said O'Neal was not traveling to Miami (or Washington), making it five straight games -- and 32 of the past 33 -- that Shaq will have missed when the Celtics return to Boston for Wednesday's season finale. The first 27 were due to a right Achilles tendon injury. The last five have been due to strained right calf. Shaq also missed the Celtics' 85-82 victory over Miami on Feb. 13 in Boston. That game was marked by Pierce going 0-of-10 from the field and scoring one point.

Jermaine O'Neal, however, is expected to play after sitting out Friday's game against the Wizards.

Dwyane Wade: His play against the Celtics this season has been -- in a word -- pathetic. We can excuse the 4-of-16 submission on opening night in Boston because he basically had missed all of training camp with a hamstring injury. But a fortnight later in Miami, Wade was 2-of-12 against the Celtics, and on Feb. 13, he was 6-of-17. Additionally, Wade has committed six turnovers in each of the three games against the Celtics.

Against the Celtics this season, Wade has averaged 12.3 points while shooting 26.7 percent from the field, 20 percent (2-of-10) from 3-point range and 64.7 percent (11-of-17) from the line. Against everyone else, he is averaging 26.3 points while shooting 50.8 percent from the field, 31.6 percent from 3-point territory and 75.2 percent from the line. He also averages three turnovers per game against non-Celtics teams.

Payback for Miami: You think the Heat might be overdue? Since the era of the new Big Three, the Celtics are 13-1 against Miami, 17-2 if you include the playoffs. As a Celtic, Kevin Garnett has never lost to the Heat in the regular season -- he missed the only Miami win in the past four seasons, a 107-99 decision on March 11, 2009. (That game may be best known for Mikki Moore picking up four fouls in the first quarter even though he didn't start the game.)

The Celtics, who have beaten the Heat eight straight times in the regular season, aren't the only good team Miami has had trouble with this season. The Heat are also 0-3 against the Bulls, 0-2 against the Mavericks and boast a 6-12 mark against Boston, Chicago, Dallas, San Antonio, Oklahoma City and the Lakers. After the latest Celtics victory, the aforementioned 85-82 triumph on Feb. 13, Wade said, "This is typical big brother stuff and you've got to get over it. You've got to get over the hump."

As they might say in South Beach, "no time like the present."
Longtime Celtics reporter Peter May is a frequent contributor to ESPNBoston.com.